#include <bits/stdc++.h>

#define all(a) a.begin(),a.end()
#define len(a) (int)(a.size())
#define fir first
#define sec second
#define fi first
#define se second
#define mp make_pair
#define pb push_back

using namespace std;

typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;

template<typename T>
bool umin(T &a, T b) {
    if (b < a) {
        a = b;
        return 1;
    }
    return 0;
}

template<typename T>
bool umax(T &a, T b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}

#ifdef KIVI
#define DEBUG for (int _____DEBUG=1;_____DEBUG;_____DEBUG=0)
#define LOG(...) prnt(#__VA_ARGS__" ::",__VA_ARGS__)<<endl
template<class ...Ts> auto &prnt(Ts ...ts) {return ((cerr<<ts<<" "), ...);}
#else
#define DEBUG while (false)
#define LOG(...)
#endif

const int max_n = 5055, inf = 1000111222;

int t, n, a[max_n], b[max_n];
int nxt[max_n], pr[max_n];

bool check(int x) {
    int pos = 0;
    for (int i = 0; i < n; ++i) {
        while (pos < n && b[pos] <= a[i] - x) {
            ++pos;
        }
        pr[i] = pos;
    }
    pos = n - 1;
    for (int i = n - 1; i >= 0; --i) {
        while (pos >= 0 && b[pos] >= a[i] + x) {
            --pos;
        }
        nxt[i] = n - 1 - pos;
    }
    for (int l = 0; l < n; ++l) {
        for (int r = l; r < n; ++r) {
            if (pr[r] + nxt[l] >= n) {
                break;
            }
            if (pr[r] + nxt[l] < r - l + 1) {
                return false;
            }
        }
    }
    return true;
}

int main() {
//    freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    cin >> t;
    while (t--) {
        cin >> n;
        for (int i = 0; i < n; ++i) {
            cin >> a[i];
        }
        for (int i = 0; i < n; ++i) {
            cin >> b[i];
        }
        sort(a, a + n);
        sort(b, b + n);
        int l = 0, r = inf;
        while (r - l > 1) {
            int mid = (l + r) / 2;
            if (check(mid)) {
                l =mid;
            } else {
                r = mid;
            }
        }
        cout << l << "\n";
    }
    exit(0);
}